The care of patients suffering from aerodigestive disorders attributed to reflux of gastric content (supraesophageal is sub-optimal. This shortcoming is for the most part due to incomplete understanding of the reflux related physiology and pathophysiology of the Pharyngo-esophageal junction and the esophagus as well lack of reliable diagnostic and effective therapeutic modalities for these common and complex conditions. Consequently the cost of current fragmented care of these patients is estimated at $54 billion annually in addition to patient suffering and diminished quality of life. There are two specific aims in this proposal: Specific Aim A: Pathophysiology of pharyngo-esophageal junction and esophageal mechanisms preventing pharyngeal reflux of gastric content. The overall goal is to define and characterize the manometric characteristics of UES incompetence associated with objectively documented pharyngeal reflux. Studies of this aim include patients suffering from both pharyngeal reflux (regurgitation) and SE-GERD healthy controls and GERD patients without regurgitation and SE-GERD and vyill: 1. Characterize and compare the UES pressure response to liquid refluxate. 2. Determine the contribution of sub-sphincteric striated esophagus to UES pressure barrier. 3. Characterize the reflux- induced esophageal motor activity. 4. Determine and characterize the mechanisms of esophago- pharyngeal reflux. Specific Aim B. Development of physiology- and pathophysiology-based diagnostic test and therapeutics Studies of this aim will: 1. Determine the reproducibility of manometric criteria for UES incompetence in prevention of pharyngeal reflux developed based on our preliminary data and studies of specific aim A. 2. Determine the ability of externally applied cricoid cartilage pressure in preventing pharyngeal reflux. 3. Determine and characterize the effect of externally applied cricoid cartilage pressure on related functions such as belch and swallow.